796 FXUS62 KCHS 111024 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 624 AM EDT Thu Oct 11 2018 .SYNOPSIS... Tropical Storm Michael will continue to move northeast through central Georgia and South Carolina today. Cooler and drier high pressure will then build in through the weekend before a coastal trough and cold front affect the area early to mid next week. && .NEAR TERM /THROUGH TONIGHT/... TS Michael is centered west of Aiken and moving quickly to the northeast. Drier air continues to be drawn into the circulation of the cyclone, and that along with Michael beginning to pull further away from the area will allow for steadily decreasing rain chances this morning. We have also removed all mention of t-storms from the forecast with minimal instability and poor lapse rates. Winds will remain elevated throughout much of the day, and this will be the main concern. Isolated to scattered power outages will occur, and driving will be difficult, especially on bridges and overpasses. The tornado threat has ended, and so we cancelled the Tornado Watch a little early. The heavy rain threat has also ended. Previous discussion... Today: Tropical Storm Michael is at it's closest approach to the forecast region early this morning, at a position near Milledgeville, Georgia as of 08Z. The storm is moving to the northeast at a steady clip, and will not far to the west of Columbia, South Carolina by 12Z, and pulling further away and into North Carolina by afternoon. The potential for any additional TC induced tornadoes is diminishing, as the region now lies generally in the E of E-SE quad of Michael's circulation. But after coordination with SPC, we will hold onto the Tornado Watch until 7 am for the Charleston tri-county district, where the best MLCAPE is located within the more discrete cells moving quickly northward from the Atlantic. Otherwise, the main rain shield with TS Michael will through our northwest tier this morning, where we have 100% PoP. But locations further to the east and southeast is experiencing a little drier air wrapping around the cyclone, and PoP will range from 20-30% near the Altamaha River to 40-70% most elsewhere in the forecast area. There hasn't been much lightning recently, so we have nothing more than slight chance t-storms during the morning. Locally heavy rainfall can still occur, but no Flash Flooding will take place. Rain chances will drop off considerably from south to north as Michael shifts further away late this morning and this afternoon, and we have PoP under 15% all locations during the early and mid afternoon, along with the removal of thunder. Winds will be the main story today, first the result of the large circulation around Michael, and then due to better mixing and larger pressure rises in the wake of the cyclone. Winds will still be as high as 25 to 35 mph sustained with gusts up to near 45 to 50 mph, and thus a continuation of the Tropical Storm Warning for all counties. There have been reports of trees down along with power outages, and this pattern will continue into this afternoon. We could see a discontinuation of some of the warnings by the 11 am NHC update, but more likely with the 5 pm package. Temperatures again begin the day unseasonably warm, with readings that are actually warmer than what normal daytime highs would be for October 11th. Extensive cloud cover this morning will diminish this afternoon, and there is sufficient insolation to allow for temps to reach the mid and upper 80s. Tonight: A cold front will kick Michael off the Delmarva and Virginia Tidewater, and this allows for cooler and much drier high pressure to build from the central U.S. We'll experience temps that will be at their lowest since May, and as skies become clear or mostly clear, upper 50s and lower 60s will be common inland from US-17, with the middle 60s closer to the coast. It will certainly feel more autumnal than it has been so far, but even these levels are still above average. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... Cooler and drier high pressure will build in behind Michael through the period. The only fly in the ointment will be a weak low pressure trough early next week which could lead to a few showers given the moister onshore flow. Temperatures should still remain at or above normal though through the period. Saturday morning will be the coolest period when areas away from the coast will be in the 50s. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... A weak coastal trough early next week will bring a few showers. A cold front should then move into the area Monday night and linger until a stronger cold front pushes through toward the end of the period with better rain chances, including some thunderstorms. Temperatures look to remain well above normal until possibly Thu. && .AVIATION /10Z THURSDAY THROUGH MONDAY/... KCHS: A broken band of showers and a few t-storms spiraling around TS Michael will move through the terminal prior to daybreak. While we continue to show MVFR conditions, brief IFR conditions with heavy rainfall is possible if there is a direct impact on the terminal. Showers associated with TS Michael with continue over or near the terminal through the late morning hours, as MVFR weather persist. There will eventually be a return to VFR conditions this afternoon as Michael passes from South Carolina into North Carolina, and moisture steadily diminishes through the rest of the day, before becoming clear tonight. SE and S winds before sunrise will clock around to the SW by late in the morning, then eventually to the SW and W in the afternoon. Sustained winds will average 20-25 kt, with gusts some 10 kt or so higher through late in the day. Two additional concerns through this morning will be the risk for isolated t-storms and also gusts in excess of 35 or 40 kt if there is a direct hit from convection. KSAV: The steady rains associated with TS Michael as it moves about 115 miles NW of the airfield will brush by before sunrise. For now we are showing MVFR conditions, but a period of IFR is certainly possible. Showers will then taper off during the morning hours, with a gradual return to VFR weather by early afternoon. S winds of 25G35 will shift to the SW during the daylight hours at similar speeds, before becoming W and slowly diminishing during the mid and late afternoon and into tonight. Extended Aviation Outlook: VFR likely through the weekend with a better chance of some brief restrictions at times thereafter. && .MARINE... Today: The large cyclonic circulation around TS Michael will produce hazardous maritime conditions across all waters today, and a continuation of the Tropical Storm Warning. South and southwest winds will be as high as 30 to 40 kt, with stronger gusts. Seas will be as high as 7 to 11 ft. There is still a risk for isolated waterspouts over the AMZ330 and AMZ350 waters, so the Tornado watch continues through 7 am. Tonight: Once the Tropical Storm Warnings end by late today, they'll need to be replaced by Small Craft Advisories, as cool advection develops in the wake of a cold front that moves through, and high pressure that builds from the west and northwest. Friday through Tuesday: Cooler/drier high pressure will build in from the north late this week with a coastal trough likely developing early next week ahead of an approaching cold front. Winds/seas should stay below Advisory levels through the period. Rip Currents: A high risk for rip currents continues today due to strong winds and moderate swells. && .TIDES/COASTAL FLOODING... Coastal Flooding: It'll take one more high tide cycle, the 10-11 am high tide, before winds turn offshore, and thus we expect additional coastal flooding to occur. Tides will peak around 7.2 to 7.6 ft MLLW at Charleston, enough for a Coastal Flood Advisory to persist. We may not reach the typical 9.2 ft MLLW at Fort Pulaski, but with the Wednesday evening high tide, where levels fell just shy of 9.0 ft MLLW, a CEMA official relayed to us that water was onto parts of Route 80 out to Tybee. With the strong southerly winds, there could be similar conditions again with the next high tide. High Surf: Breakers can still reach as high as 5 feet at the beaches today, so the High Surf Advisory continues for one more day. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...Tropical Storm Warning for GAZ087-088-099>101-114>119-137>141. High Rip Current Risk through this evening for GAZ117-119-139- 141. High Surf Advisory until 8 PM EDT this evening for GAZ117-119- 139-141. Coastal Flood Advisory until 2 PM EDT this afternoon for GAZ117-119-139-141. SC...Tropical Storm Warning for SCZ040-042>045-047>052. High Rip Current Risk through this evening for SCZ048>051. High Surf Advisory until 8 PM EDT this evening for SCZ048>051. Coastal Flood Advisory until 2 PM EDT this afternoon for SCZ048>051. MARINE...Tropical Storm Warning for AMZ330-350-352-354-374. && $$ NEAR TERM... SHORT TERM... LONG TERM... AVIATION...BSH MARINE... TIDES/COASTAL FLOODING... CLIMATE...